Prenatal Screening Options for Non-Ketotic Hyperglycinemia

Non-ketotic hyperglycinemia

Dr.
Lin, my first child had non-ketotic hyperglycinemia and passed away two weeks later due to our decision to discontinue aggressive treatment.
I would like to ask if there are any prenatal screening options available to check if our next child is healthy before we try to conceive again.
Thank you for your response.

Wen, 30~39 year old female. Ask Date: 2004/10/13

Dr. Lin Xuanpei reply Rare Disease

According to my knowledge, the prenatal diagnosis of "non-ketotic hyperglycinemia" in the country still requires sending samples abroad for testing to ensure accuracy, primarily relying on genetic testing, as enzyme analysis has its limitations.
Related matters and reliable foreign testing institutions are currently under verification, and I will inform you as soon as there is further news.
Additional information from Lin Hsuan-Pei (98-01-02): There have been successful cases of genetic testing for "non-ketotic hyperglycinemia" domestically.
Please refer to the attachment: Acta Paediatrica Taiwanica 2008; 49: 35-37.
If affected families obtain confirmed results through genetic testing, they can use this as a basis for prenatal diagnosis.
Lin Hsuan-Pei.

Reply Date: 2004/10/13

More Info

I'm truly sorry to hear about your loss. Non-Ketotic Hyperglycinemia (NKH) is a rare genetic disorder that can have severe implications for affected infants. As you consider the possibility of having another child, it's understandable that you would want to explore prenatal screening options to assess the risk of this condition.

To begin with, NKH is typically caused by mutations in the GLDC gene, which is responsible for the breakdown of glycine, an amino acid. When this process is disrupted, it leads to an accumulation of glycine in the body, which can cause neurological issues. Given that NKH is inherited in an autosomal recessive manner, both parents must carry a mutation in the GLDC gene for their child to be at risk of developing the condition.

If you and your partner are planning to conceive again, genetic counseling is highly recommended. A genetic counselor can provide you with information about the inheritance patterns of NKH and help you understand your risks. They may suggest that both you and your partner undergo genetic testing to determine if you are carriers of the GLDC mutation. If both parents are found to be carriers, there are several prenatal screening options available:
1. Preimplantation Genetic Diagnosis (PGD): If you are considering in vitro fertilization (IVF), PGD can be performed on embryos before implantation. This allows for the selection of embryos that do not carry the mutation associated with NKH.

2. Chorionic Villus Sampling (CVS): This test can be performed between 10 and 13 weeks of pregnancy. It involves taking a small sample of the placenta to test for genetic conditions, including NKH, if you are at risk.

3. Amniocentesis: This procedure is typically performed between 15 and 20 weeks of pregnancy. It involves taking a sample of amniotic fluid to test for genetic disorders. Like CVS, it can provide information about the presence of NKH if you are at risk.

4. Non-Invasive Prenatal Testing (NIPT): While NIPT is primarily used to screen for common chromosomal abnormalities, it is not typically used for single-gene disorders like NKH. However, it can provide some reassurance regarding the overall health of the pregnancy.

5. Carrier Screening: If you and your partner are not yet tested, carrier screening can be done to identify whether either of you carries the GLDC mutation. If one parent is a carrier, the other can be tested to determine the risk for future pregnancies.

It's essential to have open discussions with your healthcare provider and a genetic counselor about these options. They can help you weigh the benefits and risks associated with each screening method and guide you through the process. Additionally, they can provide emotional support as you navigate this challenging journey.

In conclusion, while the loss of your first child is a profound tragedy, there are options available to help assess the risk of Non-Ketotic Hyperglycinemia in future pregnancies. With the right support and information, you can make informed decisions that align with your family's needs and desires.

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